The head of the Food and Drug Administration asked Congress Wednesday for more authority to police pharmacies like the one that triggered a deadly meningitis outbreak, even as lawmakers questioned why the agency didn’t do more with its existing powers.

Injected to relieve pain, a steroid contaminated with meningitis has killed five people in the U.S., including one right here in Maryland. And nationally, as many as 900 people may have received a potentially dangerous injection.